#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/shm.h>
#include "shmdata.h"
int main()
{  
    int running = 1;//程序是否继续运行的标志  
    void *shm = NULL;//分配的共享内存的原始首地址   
    struct shared_use_st *shared;//指向shm   
    int shmid;//共享内存标识符 //创建共享内存   
    shmid = shmget((key_t)12345, sizeof(struct shared_use_st), 0666|IPC_CREAT);
	
    if(shmid == -1)
    {      
        fprintf(stderr, "shmget failed\n");
        exit(EXIT_FAILURE);
    }   //将共享内存连接到当前进程的地址空间
    shm = shmat(shmid, 0, 0);
    
	if(shm == (void*)-1)   
    {  
        fprintf(stderr, "shmat failed\n"); 
        exit(EXIT_FAILURE);
    }  
    printf("\nMemory attached at %X\n", (int)shm);  //设置共享内存   
    
	shared = (struct shared_use_st*)shm;   
    shared->written = 0;
    
	while(running)//读取共享内存中的数据 
    {       //没有进程向共享内存定数据有数据可读取       
        if(shared->written != 0)
        {      
            printf("zhaozonggang read: %s", shared->text);      
            sleep(rand() % 3);          //读取完数据，设置written使共享内存段可写
            shared->written = 0;         
			
            if(strncmp(shared->text, "end", 3) == 0)    //输入了end，退出循环（程序）  
                running = 0;       
        }      
        else//有其他进程在写数据，不能读取数据     
            sleep(1);  
    }   //把共享内存从当前进程中分离
	
    if(shmdt(shm) == -1)   
    {      
        fprintf(stderr, "shmdt failed\n");     
        exit(EXIT_FAILURE);
    }   //删除共享内存  
    	
    if(shmctl(shmid, IPC_RMID, 0) == -1)   
    {  
        fprintf(stderr, "shmctl(IPC_RMID) failed\n");  
        exit(EXIT_FAILURE);
    }  
    exit(EXIT_SUCCESS);
}